The following abbreviations and terms are herewith defined:                3GPP third generation partnership project        E-UTRAN evolved UTRAN        GERAN global system for mobile communication (GSM) enhanced data rate radio access network        IMSI/IMEI international mobile subscriber/equipment identity        LTE long term evolution of 3GPP (also E-UTRAN or 3.9G)        Node B base station, e.g., an evolved (e-)Node B of an LTE system        UE user equipment (e.g., mobile equipment/station        UMTS universal mobile telecommunications system        UTRAN UMTS terrestrial radio access network        
3GPP is standardizing the long-term evolution (LTE) of the radio-access technology which aims to achieve reduced latency, higher user data rates, improved system capacity and coverage, and reduced cost for the operator. One particular aspect of LTE relevant to these teachings is termed therein a closed subscriber group CSG. Annex F of 3GPP TS 36.300 (V8.1.0, 2007-06; Overall Description; Stage 2), describes a concept of Home e-node Bs that form one or more CSG cells (attached as Appendix A of the priority document). Access is restricted in these CSG cells due to quality of service QoS requirements and regulatory issues in sharing the backhaul link at that location.
One prior art disclosure relevant to the environment in which these teachings are appropriate is Finland patent application no. 20075252, filed on Apr. 13, 2007 and entitled “Method, radio system, mobile terminal and base station” (attached as Appendix B to the priority document). There is described the concept of ‘local breakout services’ in which a user equipment detects availability of a local breakout service to an internet protocol gateway, starts network entry, and configures its protocol stack on the basis of configuration data received from the local breakout service. This local breakout service may be considered in some respects analogous to the home e-node B and the CSG cells described in 3GPP TS 36.300 noted above.
The registered owner of the home e-node B adds subscribers to its user group, and it is those members of the user group that are allowed access to the CSG cell. Because one or more home e-node Bs can be linked to form more than one CSG cell contiguous with one another, it is convenient to term them a CSG network. A CSG network is a network composed of one or more cells with access permissions managed at least partially by final consumers. Those subscribers registered as members of the user group are CSG members. A CSG member is a wireless service (cellular) user registered to the CSG network by the CSG administrator, and once registered is allowed to access the CSG network. Those users or devices not registered to the CSG are not allowed access to it, hence the term closed subscriber group. In CSG networks, only the devices (user equipment or UEs) that have been granted permission to access a CSG network may camp or connect to that network. Examples of CSG cells include a home e-node B (LTE cells that are purchased by the consumer) or corporate cells (cells that are hired or owned by a company) and “commercial” cells (cells that are owned by retailing companies, supermarkets etc). It is the responsibility of the CSG administrator to register a user as CSG member.
While the CSG network can control and modify the subscribers that form its user group quickly, access is restricted to registered subscribers and closed to other users. The procedure in which a user is added as a CSG member of a CSG network is generally as follows. The CSG administrator adds the IMSI/IMEI or phone number to the operator's database; the operator sends a list of one or more CSG network identifiers to the user via NAS signalling; and once user receives the NAS information, the user becomes a CSG member and therefore is allowed to access all the cells that belong to the same CSG network identifier.
Mobility of the user group members between the CSG network and other cells that are ‘open’ (non-CSG cells, whether they be E-UTRAN, UTRAN, GERAN, or others) is described also at Annex F of 3GPP TS 36.300 referenced above so that user group members prioritize their CSG network over other cells when within range of the CSG network. In this manner the CSG concept expands overall coverage of the public, non-closed network, though only to the user group members.
The concept of the CSG networks may be considered useful in the context of a corporate or university campus, or a retail establishment. The corporation or university allows its employees/students free or low cost access to the CSG by enrolling them into the appropriate user group while restricting others from free riding on the service. Adding members to these groups on an ad hoc basis, such as visiting speakers or professors, is not a difficult matter as these additions will generally be only occasional.
Businesses on the other hand may want to provide their customers with free or low cost access in order to lure them and encourage them to linger longer and possibly purchase more of the business' regular products or services. For example a restaurant or café may prefer to provide a free or low-cost Internet access to its customers in order that they choose that establishment over competitors and stay longer once there. Vodafone® has indicated a desire to allow public users access to restricted networks. But in these instances the ‘public’ users' would constitute the vast majority of users on the closed network, and each would have to be registered individually as above into the user group to enable their access to the CSG network. It is quite impractical and perhaps not even possible under current understanding of CSGs for a café or restaurant to add such a potentially large number of users' IMSIs (or phone numbers) to its user group database to enable them access to its CSG network.
What is needed in the art is a way to enable public, non-members of a CSG user group access to the operator's CSG network. No prior art solution is known; the only option of which the inventors are aware is to register the potential user into the user group and allow access as normal.